The present invention relates to chest compression devices and in particular to a high frequency chest wall oscillator device.
Manual percussion techniques of chest physiotherapy have been used for a variety of diseases such as cystic fibrosis, emphysema, asthma, and chronic bronchitis, to remove the excess mucus that collects in the lungs. To bypass dependency on a care giver to provide this therapy, chest compression devices have been developed to produce high frequency chest wall oscillation (HFCWO), the most successful method of airway clearance. In addition, these devices can be utilized for induction of high quality sputum samples for screening and diagnosing a number of pulmonary disorders such as lung cancer, asthma, chronic obstructive pulmonary disease (COPD), tuberculosis, Pneumocystis carinii pneumonia (PCP), inflammation, and infection.
The device most widely used to produce HFCWO is the ABI Vest Airway Clearance System by American Biosystems, the assignee of the present application. A description of the pneumatically driven system can be found in the Van Brunt et al. patent, U.S. Pat. No. 5,769,797, which is assigned to American Biosystems, Inc. Another pneumatic chest compression device has been described by Warwick et al., U.S. Pat. No. 4,838,263.
Pneumatically driven HFCWO produces substantial transient increases in the airflow velocity with a small displacement of the chest cavity volume. This action produces a cough-like shear force and reduction in mucus viscosity that results in an upward motion of the mucus.
A shortcoming of the design of the vests used by these devices is that the compressions are not concentrated on the region of the chest which directly surrounds the lungs. An inflatable air bladder that provides the compressive force extends all the way around the patient including the back. The bladder has a rather large volume which renders it inadequate to create the magnitude of force necessary on regions encompassing the lungs to clear the lungs of mucus or induce deep sputum that, for example, provides optimal samples for lung cancer screening. In addition, since the vests close in the front, the air bladder is not continuous over the chest. The air bladder""s design does not allow it to reach to the highest lobes of the lung, and it extends too low resulting in compression on the stomach, a particular problem for short adults and children. This results in inefficient and insufficient mucus induction and mobilization. Thus, there remains a need to design a vest which focuses the force in the proper regions to give optimal results.
Prior art vests, when fastened to the patient and not inflated, take on the shape of the torso. When inflated they bow outward. The outer material is not rigid enough to maintain its shape, and so the vest takes on a more circular shape. The outward force, which causes the bowing, increases the volume of the air bladder, but it is more desirable to have the increase in volume result from a change in the shape of the chest. Therefore, a vest which maintained its shape would be more efficient, because the outward force that causes the vest to change shape would not cancel out the inward compressive force.
The previous vests were designed for one person to use multiple times. The durable material that is used makes the vest too expensive to be utilized for a single use and cannot be easily and cleanly burned for disposal. For analysis of sputum samples, though, generally the patient only needs the vest one time. The vests, however, cannot be used by multiple patients, because mucus is expelled onto the vest by each patient, and the vests cannot be sterilized between uses. Therefore, there is also a need for a vest which is cost effective for single-use.
The present invention is a pneumatic chest compression vest which loosens and helps remove mucus from a person""s lungs or induces production of sputum samples for further diagnostic analysis. The vest is designed to focus the compressive force on the region of the chest which encompasses the lungs.
The vest includes a front panel having a central bib portion and side portions. An air bladder is mounted to the inner surface of the front panel. Air ports and removable air couplings on the front panel are in communication with the air bladder. When inflated, the air bladder applies a compressive force focused on the region of the chest which encases the lungs.
The vest also includes a belt that connects to the front panel and extends around the person and across the outer surface of the front panel. The belt contains a plurality of longitudinally spaced holes which align with the air ports on the front panel. The air couplings extend through the holes in the belt and the air ports to secure the vest and connect the air bladder to a source of oscillating pneumatic pressure.